I. Field of the Invention
This invention relates to devices and methods for removing body tissue. More particularly, the present invention relates to devices and methods for removing body tissue involving the use of a brush or brush-like element capable of collecting, carrying, or otherwise receiving body tissue for removal.
II. Discussion of the Prior Art
A large variety of pathologies affecting many different body tissues indicate the use of tissue ablation (i.e., removal or destruction of a tissue). Examples of such procedures include knee meniscectomy, knee synovectomy, chondromalacia and tears, loose body debridement, lateral retinacular release, plica removal, ligament and tendon release, contouring and sculpting of articular surfaces, debridement of inflamed synovial tissue, capsulectomy in the knee, complete or partial resection of internal organs, tumors and lesions.
Tissue ablation can be accomplished using many different ways, the two main categories consisting of mechanical and energy focusing means. Mechanical tools are used to cut away the targeted tissue. Thermal energy has also been used which heats the targeted tissue until the cells die. Lasers, radiofrequency waves, microwaves, ultrasound, and cryotherapy have all been used in thermal techniques. In a related technique, an electrical current is used to excite a fluid, creating a plasma layer. The highly energized plasma layer then incrementally disintegrates layers of the tissue.
The existing techniques suffer from a host of disadvantages. Typically, mechanical devices are small and remove tissue in very small increments. As a result, when large amounts of tissue must be removed the excision time may be exorbitant. The energy focusing techniques, in addition to suffering from the time disadvantage of the mechanical devices, are further limited. The energy levels applied to the tissue must be conservatively regulated to avoid damaging tissue beyond the targeted tissue.
One procedure, in particular, that is hindered by the existing devices and techniques is a spinal discectomy (i.e., removal of intervertebral disc material). Each disk is composed of an annulus fibrosus, a nucleus pulposus, and a pair of end caps which couple the annulus fibrosus and nucleus pulposus. The annulus fibrosus is an annular multi-layered composite structure. Each layer is constructed of fibrous tissue and fibrocartilage with the fibers of each layer ordered and oriented generally in the same direction. The fibers of adjacent layers pass in opposite directions so that when the layers are combined they create a mesh of concentric rings. The central cavity of the annulus houses the nucleus pulposus, which is a semi-gelatinous, highly elastic material. The final components are end caps constructed of thin layers of hyaline cartilage that cover both the top and bottom of each spinal disk. The end caps cover both the annulus fibrosus and the nucleus pulposus and assure that the nucleus pulposus remains within the confines of the annulus fibrosus.
Oftentimes, disks become herniated, or bulge, due to structural damage to the annulus fibrosus. The bulging disk may place pressure on nearby nerves, which can lead to debilitating pain, numbness or muscle weakness. Treatments used to reduce the affects of a damaged disk range from bed rest to spinal fusion. Due to the major shortcomings of those extreme treatments they are often not desirable. A discectomy, either full or partial, can help to balance the burdens and benefits of bed rest and fusion or help prepare the intervertebral site for procedures like fusion.
When a partial discectomy is performed, a portion of the nucleus pulposus of a herniated disc is excised. Partially removing the nucleus material can reduce the pressure exerted by the nucleus on the annulus and reduce the bulging. In this procedure, the surgeon must first make an appropriate incision through the skin and other tissue layers, and then typically create an access hole through the herniated annulus (i.e., an annulotomy) to treat the offending tissue. Such access holes are created with a variety of surgical instruments including scalpels, probes, trephines, etc., and the access hole may range in size from 3 to 6 mm in diameter.
Upon entry into the interior annular space, the surgeon removes the offending tissue. The tools typically used are only able to remove small portions of tissue with each approach. As a result, removal of the tissue during a discectomy can take an exorbitant amount of time. In addition, in some cases, when ablation of the verterbral body surfaces adjacent to the disc is required, an additional tool must be used adding additional time and steps to the procedure. The additional time requirement of this procedure gives rise to a need for tools and methods for performing rapid discectomy and end plate ablation.
The present invention is directed at addressing this need and eliminating, or at least reducing, the effects of the shortcomings of the prior art systems as described above.